Human urine

Urine or is liquid waste
excreted by the
kidneys and is produced by a process of filtration from
blood.
This waste is eventually expelled from the body in a process
known as
urination.

Human Urine Sample

Composition

Urine is the by product or fluid secreted by the kidneys,
transported by the ureters to the urinary bladder where it is
stored until it is voided through the urethra. It is a
transparent solution that is clear to amber in
color,
and usually is light yellow. Urine is made up of a watery
solution of metabolic wastes (such as
urea),
dissolved salts and organic materials. Fluid and materials being
filtered by the kidneys, destined to become urine, come from the
blood or
interstitial fluid. The composition of urine is adjusted in
the process of reabsorption when essential molecules needed by
the body, such as
glucose, are reabsorbed back into the blood stream via
carrier molecules. The remaining fluid contains high
concentrations of
urea
and other excess or potentially toxic substances that will be
released from the body via urination. Urine flows through these
structures: the
kidney,
ureter,
bladder, and finally the
urethra. Urine is produced by a process of
filtration,
reabsorption, and tubular secretion.

Urine contains large amounts of
urea,
an excellent source of
nitrogen for plants. As such it is a useful accelerator for
compost. Urea is 10,000 times less toxic than
ammonia and is formed by the combination of the byproducts
of deamination (2 NH3 molecules) and cellular
respiration (1 CO2 molecule). Other components
include various inorganic
salts
such as
sodium chloride (the discharge of
sodium through human urine is known as natriuresis).

Color

The typical clear yellow or yellow-orange (usually a sign of
dehydration) color of urine is caused by the pigment
urochrome, but also from the degradation products of
bilirubin and
urobilin. Unusual coloration may be the result of certain
food products such as
betacyanin as found in red
beets.
Also, removal of excess B vitamins from the bloodstream may
cause a yellowing. A common prank is to trick someone into
drinking
methylene blue, resulting in blue urine. Abnormal coloration
from bleeding within the urinary system is termed
hematuria (blood in the urine), a symptom that needs medical
attention. Dark orange to brown urine can be a symptom of
jaundice or
Gilbert's syndrome. "Melanuria" refers to black or
dark-colored urine and may be caused by a
melanoma.
Porphyria may also change the color of urine to a reddish or
brown.

Turbidity

Turbid urine may be a symptom of a bacterial infection, but
can also be due to crystallisation of salts in the urine (e.g.
calcium phosphate), which will dissolve if
acetic acid (vinegar) is added. If turbidity occurs together
with pain in the bladder region or during urinating, it is most
probably due to an infection.

pH

The pH
of urine is close to neutral, i.e. 7, but can normally vary
between 4.5 and 8. Strongly acidic or alkaline urine may be a
symptom of a disease.
[1]

Amount

The amount of urine produced depends on numerous factors
including state of hydration, activities, environmental factors,
size, and health. In adult humans the average production is
about 1 - 2 L per day. Producing too much or too little urine
needs medical attention:
Polyuria is a condition of excessive production of urine (>
2.5 L/day), in contrast to
oliguria where < 400 mL are produced per day, or
anuria with a production of < 100 mL per day.

Function

Urination is the primary method for excreting toxins,
chemicals and
drugs from the body. These chemicals can be detected and
analysed by
urinalysis. Cellular metabolism results in a buildup of
toxic nitrogen compounds, or nitrogenous waste. Since this waste
is toxic, most animals have excretory systems (in humans this is
known as the
Urinary system, which consists of the
Kidneys,
Urinary Bladder,
Ureter, and
Urethra) to rid themselves of this waste. The kidneys
extract the nitrogenous wastes from the bloodstream, as well as
excess water, sugars, and a variety of other chemicals.

In cases of kidney or
urinary tract infection (UTI), the urine will contain
bacteria, but otherwise urine is virtually
sterile and nearly odorless when it leaves the body.
However, after that, bacteria that contaminate the urine will
convert chemicals in the urine into smelly chemicals that are
responsible for the distinctive
odor
of stale urine; in particular,
ammonia is produced from urea.

Some diseases alter the quantity and consistency of the
urine, (e.g.,
sugar
in the urine is a sign of
diabetes).

Urine in medicine

Examination

Physicians in all ages have resorted to the inspection and
examination of the urine of their patients.
Hippocrates described urine examination.
Hermogenes wrote about the color and other attributes of
urine as indicators of certain diseases.
Diabetes mellitus got its name because the urine is
plentiful and sweet. A
urinalysis is a medical examination of the urine and part of
routine examinations. A culture of the urine is performed when a
urinary tract infection is suspected. A microscopic
examination of the urine may be helpful to identify organic or
inorganic substrates and help in the diagnosis.

The color and volume of urine can be reliable indicators of
hydration level. Clear and copious urine is generally
a sign of adequate hydration, dark urine is a sign of
dehydration. The exception is when
alcohol,
caffeine, or other
diuretics are consumed, in which case urine can be clear and
copious and the person still be dehydrated.

Application

The use of
urine therapy as a medical treatment or daily health regimen
is uncommon.
Aztec
physicians used urine to clean external wounds to prevent
infection, and administered it as a drink to relieve stomach and
intestine problems. Purported beneficiaries of the 'urine cure'
include
Mohandas Gandhi,
Jim Morrison, and
Steve McQueen.[2]
Its medicinal properties have also been used in China as a part
of holistic medicine, and in India, especially as part of the
traditional Indian medicine,
Ayurveda, under the name
Amaroli.

Other uses

Ancient uses

The ancient
Romans used urine as a bleaching agent for cleaning clothes
and there are even isolated reports as a teeth whitener
(supposedly originating in what is now
Spain).

In
Siberia, to communicate with the spirits, the
Koryak people drank the urine of another who has consumed
fly agaric (an
entheogenic
mushroom that is occasionally fatally poisonous), or of one
who has in turn drunk urine of like source. According to Koryak
tradition, sometimes the urine of
reindeer that had eaten fly agaric would be ingested --
although there are skeptics who claim that an animal would
naturally avoid this mushroom because of its deep red color --
and reindeers are reported to lick the ground where users of fly
agaric had urinated. The potency of the mushroom does not
decrease significantly until around the seventh drinker, because
the
muscimol from fly agaric is essentially unaltered after
being secreted from the kidneys. Not only does this conserve the
mushrooms, but it also eliminates unpleasant side-effects caused
by
muscarine, as this does not pass through urine and only the
initial ingestor must experience the unpleasant effects.

Fertilizers

Urine has applications in gardening and agriculture as a
fertilizer. Gardeners often recommend a dilution of 10-15
parts water to one of urine for application to pot plants and
flower beds during the growing season; pure urine can chemically
burn the roots of some species. Urine typically contains more
than 50% of the
nitrogen and
phosphorus and
potassium content of whole
sewage, and is widely considered as good as or better than
commercially-available chemical fertilisers or stabilised sludge
from
sewage plants. Urine is also used in
composting to increase the nitrogen content of the
mulch,
accelerating the composting process and increasing its final
nutrient values.

Urine is also being actively considered as a fertilizer for
use in food-crop agriculture in developed countries. Studies
into its feasibility and safety usually indicate that it is an
acceptable alternative to chemical fertilisers and stabilised
sludge. However, the technology to implement its use on a large
scale has not been developed, and is considered too expensive.
There are also concerns over its safety regarding the potential
for transmitting infectious disease and refluxing
xenobiotic compounds (associated with toilet-cleaning
products and prescribed drugs expelled in urine) in the human
food chain. Proponents of adopting urine for this use usually
claim the risks to be negligible or acceptable, and point out
that sewage causes more environmental problems when it is
treated and disposed of compared with when it is used as a
resource. Critics generally agree that more research is needed
into how the resource is to be collected, processed and handled.

A few people use urine as a crop fertilizer. These include
organic farming cooperatives and
eco-villages where special urine-diverting toilets with
collecting tanks are installed. Many of these also employ
concepts such as
greywater irrigation and the
composting of
fecal
matter. Many are the subject on ongoing feasibility studies
sanctioned by governments and private organisations. These
people generally reject safety concerns over its use on food
crops provided that it is used with common sense. For example,
application to fruit trees is considered safer than to bushes
and especially root crops. It is also considered sensible to
cease application at a safe interval before harvesting. However,
the use of urine for this purpose is even rarer than its use on
ornamental gardens.

In developing countries, the application of pure urine to
crops is also rare. However, whole, untreated sewage, termed
night soil, is often applied to crops and is considered
essential. It is worth noting that this practice is not new and
has been applied, along with
crop rotation schemes, for thousands of years.

In
Japan, urine used to be sold to farmers who would process it
into fertilizers.

Survival uses

Shipwrecked or people otherwise adrift at sea for long
periods often resort to drinking their urine when no rainwater
is available,
seawater being unsuitable. People stranded in deserts often
also drank urine to prevent life-threatening dehydration from
setting in. However, this desperate measure achieves little to
delay death from thirst as urine dehydrates one in the same
manner saltwater does.

During
World War I, the
Germans experimented with numerous poisonous gases for use
during war. After the first German
chlorine gas attacks, Allied troops were supplied with masks
of cotton pads that had been soaked in urine. It was believed
that the
ammonia in the pad neutralized the chlorine. These pads were
held over the face until the soldiers could escape from the
poisonous fumes, although it is now known that chlorine gas
reacts with urine to produce toxic fumes (see
chlorine and
Use of poison gas in World War I).

Urine has also been historically used as an antiseptic. In
times of war, when other antiseptics were unavailable, urine,
the darker the better, was utilized on open wounds to kill
bacteria.

Cultural uses

Some people incorporate urine into their sexual activity. A
person with
urolagnia may urinate on his or her partner or enjoy being
urinated upon.

The consumption of urine can be seen in the films
CKY and
Jackass in the form of a frozen confectionery. After
scooping ice into a cone he then urinates into it forming a
slush drink which he then consumes. However, shortly afterwards
he became sick.

History

The yellow color of urine was previously thought to come from
gold.
Alchemists spent much time trying to extract gold from
urine, and this led to some interesting discoveries such as
white
phosphorus, which was discovered by the German alchemist
Hennig Brand in
1669
when he was distilling
fermented urine. In
1773
the French chemist
Hilaire Rouelle, discovered the organic compound
urea
by boiling urine dry.